In existing art, Lung cancer, a kind of malignant cancers, has become the first killer to human's health. Incidence of lung cancer increases at 11.90% in recently 10 years due to the aggravating environmental pollution. Up to 2000, there are more than 10,000,000 cases of malignant cancers in the world, in which there are 1,239,000 cases of lung cancer. Up to 2000, there are about 6,200,000 persons died by malignant cancers, in which there are 1,103,000 persons died by lung cancer. The lung cancer has become first deadly malignant cancer. Now there are 1,500,000 to 1,800,000 persons died by lung cancer each year in the world. In China, the rate is 83.43 persons per 100,000 persons. There are more than 1,000,000 cases each year in China, and there are more than 600,000 persons died by lung cancer. Therefore, how to find the effective new drug for anti-lung cancer has become the hot problem in the medical field.
The current methods and related drugs for treatment of the lung cancer, surgical resection, radiation therapy, and chemotherapy, have some limitation. Once the patient is clinically diagnosed with lung cancer, 80% patients will lost the chance of surgical resection. Radiation therapy will bring damage to normal tissues, and this therapy method cannot be used in widely range. Chemotherapy will bring general cytotoxicity with high dose. The drug therapy will bring some side effects to liver, kidney, bone marrow and digestive system so that the treatment effect is lower. Intervention therapy is difficult to deal with the continuously disseminated metastases of cancer cells. Molecular targeting (gene) therapy still has many problems need to be solved, for example, vector construction, linkage of vector and projectile, the distributing in human body, and changes in the metabolic process, etc.
Through prior research, inventors of the present invention find that a glycoprotein marked PE-40 which extracted from limax has direct inhibitory effect to the small cell lung cancer, and chemotherapy drug such as DDP and 5-FU, and cytokines such as TNF-α will enhance the inhibitory effect to the small cell lung cancer, and these drugs have no toxicity and side effects. Though glycoprotein PE-40 is better than the other drugs, the glycoprotein is easy to sensitized and unstable due to the protein composition, which limits its apply range. The object of the present invention is to remove the protein and retain the polysaccharide of the glycoprotein PE-40, and try to keep the inhibitory effect. The dextran of the present invention could interfere with the normal metabolism of DNA and RNA of cancer cells, and promote the death of cancer cells, and inhibit the foci of the cancer.
The present invention further provides the polysaccharide composition KY-1 of the above polysaccharide mixture original from glycoprotein PE-40, and determinates the molecular structure of a sub-composition KY-1-1 of the polysaccharide KY-1.